Aircraft construction



Oct 17, 1939. J. M. JAC'BSON Er AL 2,116,811

AAIRCRAFT CONSTRUCTION Filed DSG. 31. 1958 2 Sheets-Sheetl tn ....23226m OLI., 2 E225@ NIA/WW1.

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ATTORNEY.

Patented Oct. 17, 1.939y

unirse STATE-s AIRCRAFT CONSTRUCTION Joel M. Jacobson and MichaelWatter, Baltimore, Md., assignors to The Glenn L. Martin {lompany,Baltimore, Md.

Application December 3l, i938, Serial No. 248,738

6 Claims. (al. 24d-77) flhe invention relates to the automatic controlof aircraft wing iiam in accordance with the speed.

ln the operation of an aircraft in which the wings are provided withflaps in the known manner, it is dangerous to fly the plane above acertain critical speed when the flaps are in their lower or extendedportion. The object of the present invention is to provide an electrical10 switch mechanism which will control the flap moving mechanism in sucha manner as tc raise the flap whenever the aircraft exceeds suchcritical speed. v

A further object of the invention is to provide an electrical mechanismof' a simple nature for producing this action.

A further object is to provide alnovel type of speed control switch forcausing the mechanism to operate to raise the flaps whenever. the

speed exceeds the critical.

The invention in general comprises a pressure controlled electric switchwhich is combined with a manual or other ap controlling mechanism insuch a manner that it will automatically raise the flaps whenever theaircraft exceeds the critical speed above which operation is dangerous,

by means ci the increased pressure in a suitably constructed mechanismresulting from such increased speed.

Further objects and advantages of the invention will appear more fullyfrom the following description, particularly when taken in conjunctionwith the accompanying drawings which form a part thereof.

In the drawings:

Fig. 1 shows diagrammatically one type of switch and electric circuitfor accomplishing the result of the invention. A

Fig. 2 is a diagram of adifferent type of mechansm.

For the operation of the flaps inthe usual electrically operated devicethere x.is provided a motor L which upon rotation in opposite directionswill raise or lower the flaps. Current is supplied to the motor from asource 4 through a line 6 and movable switch contact 8. Contact 8 mayengage'either a contact l0, which supplies current through a line I2 toone winding I3 ci the motor of a conventional type shown, for example,in the patent to Sperry No. 1,896,805, so as to turn the same in adirection to raise the flap or retract it Withinthe Wing, or to acontact I4 supplying current through a line i6 to the other winding I1of the motor in a direction to cause the motor to turn in such adirection as to lower the flap or move it out from the wine. The currentfrom the motor flows from line i8 to the negative side ci the circuit.

The movable switch member t is controlled by two relays 26 and 22.Current is supplied 5 to these relays from a suitable source 24 througha manually operable switch 26 capable of selectively engaging twocontacts 2,8'and 30. Contact 28 supplies current through wire 32 to re-'lay 20 and contact 30' supplies current-through 10 wire 34 to relay 22.Obviously as switch member 26 is moved upwardly or downwardly relays 20or 22 will be energized and movable switch member 8 will be shifted tosupply current in the proper direction to the motor.

Within each of the lines 32 and 34 there is a switch 36, these twoswitches constituting the uplimit and down-limit switches respectively.This is a conventional provision in a device of this type, and theseswitches are operated by the movement of the flap when it reaches itsupper or lower extreme positions,and are at that time opened. Thus it isimpossible to supply current to the motor in a direction to lift the'flap when the flap is in its uppermost position, or in a direction tolower the flap when the flap is in its lower position.

The present invention comprises the provision in a device of this typeof a speed controlled switch which is shunted between the source ofcurrent 24 and the line 32. One wire 38 is connected to the source ofcurrent 24 and another wire 4B to the contact 28. These wires terminatein spaced contacts 42 arranged within a box Mi. Air under apredetermined pres- 35 sure is supplied to this box through alpipe 46.

Arranged within `the box 44 are two dia.- phragms 58 forming betweenthem a chamber t 50. The space between the diaphragms is connectedthrough a pipe 52 to the usual speed indicator comprising a Pitot head,or, in other words, a device arranged in such a manner that the pressurein the line increases, or at least varies, as the speed of the aircraft'increases.

Assuming that a predetermined constant pressure is provided by pipe 46in* the box 44, as the pressure in space 50 varies, it is obvious thatthe diaphragms will lmove towards and from each other. -When thepressure in the space 50 increases to a certain extent, contact member54 mounted on the lower diaphragm will engage the two contacts 42 andclose a circuit therebetween. i Assuming now that the airplane is inflight. When the pilot wishes to move the ap down- 55 wardly, the switchmember 26 is moved downwardly and closes a circuit to the down windingI1 of the motor, so that the ilap moves down. Switch 26 and contactmember 6 are both `normally open switches, so that when the flap movesdownwardly to its desired position the pilot releases switch 26, whichassumes its neutral position as does contact 3.

Now if the speed of the aircraft exceeds the critical speed above whichit is dangerous to operate with the flaps down, the pressure in chamber50 will increase sufficiently to move contact 54 to close the circuitacross contacts 42. Current will then flow from the source 24 throughline 38, contact 42, contact 54, contact 42, line 40, contact 26, line32, including uplimit switch 36, to relay 26. This will raise movablecontact 8 and current will How from Source 4 through line 6, contact 6,contact Il and line I2 to the up winding I3 of the motor 2. The motorwill then lift the ilap or move it towards its retracted position andwill contlnue to do so as long as the speed exceeds the critical speed,or until the flap reaches its fully retracted position, at which timethe up limit switch 36 will open and the motor will of course cease tooperate.

The fo1\n of the invention shown in Fig. 1 presents the possibility thatthe pilotmight keep the flap down by holding the switch 26 so that equalamounts of current will be supplied to relays 20 and 22 and contact 8would not be operated. Fig. 2 shows a modification in which this isimpossible. The source of current 24, switch 26, contacts 28 and 30 andautomatic switching mechanism including the-box 44 and contact 64 arethe same as shown in Figli. Contacts 28 and 36 supply current to lines32 and 34 respectively. These lines lead to a switch mechanismcomprising a movable contact 62 connected to line 34 and a fixed contact64 cooperating therewith connected to a line 66; and a relay 68connected to line 32 and to outlet'line 16. Relay 68 is arranged in sucha manner that when current flows through line 32 to line 'III relay 66will be energized and will move contact 62 to open position so as tobreak the circuit between lines 34 and 66.

In lines 66 and 'l0 there are provided the up llimit and down limitswitches 36, and lines 66 and III then lead respectivelyto lines I6 andI2 of the motor, connected to the down', and up windings I1 and I3respectively.

The mechanism operates in general in the same manner asin Fig. 1. Duringnormal operation, switch 26 may engage contact 3l to energize line I6and thus cause the motor to move the flap downwardly. Line 32 is notenergized and therefore contact 62 remains closed. When switch 26 ismoved to engage contact 26, line I2 is energized to operate the motor tomove the flap upwardly. Relay 66 lifts contact 62 and thus breaks thedown circuit at this point, which of course is immaterial since thecircuit is already broken at contact 36.

If, however, contact 55 of the switch 44 is in engagement with contacts42, because the critical speed has been exceeded, current will flowthrough line 32 regardless of the position of switch 26 to drive themotor in the up direction. Relay 68 will move contact 62 and break thedow circuit. Now even 4though the pilot should hold the switch 26 in thedown position, current cannot ilow to the down side of the motor andtherefore the :dan will be raised.

While we have described herein some embodiments of our invention, wewish it to be understood that we do not intend to limit ourselvesthereby except within the scope of the appended claims.

We claim:

1. In a device for controlling the iiap of an aircraft, comprising anelectric motor connected to the flap to raise orlower the same, means tosupply current to the motor to cause the same to turn in oppositedirections to raise or lower the flap, said means including a source ofcurrent and a movable switch member normally connected to said sourceoperable in dilerent positions to control the supply of current to themotor, and means also normally connected to a source of current at thesame time as said switch member and controlled by the speed of theaircraft to supply current to the motor in a direction to raise the iiapwhen the aircraft exceeds its critical-speed.

2. In a device for controlling the flap of an aircraft, comprising anelectric motor connected to the flap to raise or lower the same, meansto supply current to the motor to cause the same to turn in oppositedirectionsl to raise or lower the flap, said means including a movableswitch member operable in diierent positions to control the supply ofcurrent to the motor, a switch normally operatively shunted across saidswitch member and adapted when closed to supply current to the motor ina direction to raise the flap, and means controlled by the speed of theaircraft to close said switch when the aircraft exceeds its criticalspeed. I

3..d In a device for controlling the flap of an aircraft, comprising anelectric motor connected to the flap to raise or lower the same, meansto supply current to the motor to cause the same to turn in oppositedirections to raise or lower the flap, said means including a movableswitch member operable in diilerent positions to control the supply ofcurrent to the motor, a switch normally operated shunted across saidswitch member and adapted when closed to supply current to the motor ina direction to raise the flap, and uid pressure means controlled by thespeed of the aircraft to close said switch when the aircraft exceeds thecritical speed.

4. In a device of the character described, a motor having two windingsfor causing the same to turn in opposite directions, a pair of fixedcontacts connected to each of said windings, a first movable contactengageable with both said first pair of fixed contacts, a first sourceof current connected to said first movable contact, relays adapted andarranged to move said first movable contact to engage said iirst pair offixed contacts, a second source of current, a second pair of iixedcontacts connected to said relays respectively, a switch for selectivelyconnecting said second source of current to said second pair of fixedcontacts, and an automatic control circuit normally operatively shuntedacross said Asecond source of current and one of said second pair offixed contacts, said control circuit including means controlled by fluidunder a pressure which varies with the speed of the aircraft to supplycurrent from said second source to said contact of the second pair whenthe aircraft exceeds a critical speed.

5. In a device of the character described, a. motor having two windingsfor causing the same to turn in Opposite directions, a pair of xedcontacts connected to each of said windings, a

rst movable contact engageable with both said first pair of fixedcontacts, a first source of current connected to said rst movablecontact, relays adapted and arranged to move said rst movable contact toengage said first pair of xed contacts, a second source of current, asecond pair oi xed contacts connected to said relays respectively, aswitch for selectively connecting said second source of current to saidsecond pair of fixed contacts, and an automatic control circuit normallyoperatively shunted across said second source of current and one of saidsecond pair ot' fixed contacts, said control circuit including a thirdpair of spaced xed contacts,

diaphragm means forming a space, a second movable contact carried bysaid diaphragm means and engageable with said third pair of fixedcontacts to connect the same, and means to supply to said space iiuidunder a pressure whichvaries with the speed of the aircraft. f

6. In a device of the character described, a motor having two windingsfor causing the same to turn vinv opposite directions, a pair of fixedcontacts connected to each of said windings, a first aircraft.

movable contact engageable-with both said first pair of iixed contacts,a rst source of current connected to said first movable contact, relaysadapted and arranged to move said rst movable contact to engage saidi'lrst pair of iixed contacts,

-a. second source of current, a second pair of xed contacts connected tosaid relays respectively, a

'switch for selectively connecting said second source of current to saidsecond pair o! fixed contacts, and an automatic control circuit normallyoperatively shunted across said second source of current and one of saidsecond pair of ilxed contacts, said control circuit including achamber,.a third pair of spaced xed contacts arranged in said chamber,spaced diaphragms in said chamber forming a space therebetween, a secondmovable contact carried by one of said diaphragms and engageable withsaid third pair of xed contacts to connect the same, and means' tosupply tothe space between said diaphragm fluid under a pressure whichvaries with the speed of the JoEL M. JACoBsoN. mcHAEr.. wa'rrria..

